The spinning continues (as does the Christmas knitting, but that isn't yet bloggable)...
First off the spindle was a braid of merino / silk blend dyed by Old Maiden Aunt in the colourway 'teal deer'.
Next up was a rainbow felting sample pack from Diva Design studios in Moray. The fibre wasn't listed, but a bit of detective work makes me think it was mostly merino with an occasional bit of silk blended in.
On reflection, I think that a plying ball is really useful for making a two ply, or a three ply from individual singles, but the work involved in putting a chained three ply onto the ball is probably not worth any time and convenience saved during plying.